Study: Pollution may hamper bees' 'noses'

Sunday

Oct 6, 2013 at 12:01 AMOct 6, 2013 at 1:46 PM

When it comes to zeroing in on nectar-rich flowers, worker honeybees rely on their sense of smell. But research suggests pollution from diesel exhaust might fool the honeybee's "nose," making its search for flowers more difficult.

When it comes to zeroing in on nectar-rich flowers, worker honeybees rely on their sense of smell. But research suggests pollution from diesel exhaust might fool the honeybee’s “nose,” making its search for flowers more difficult.

In a paper published recently in Scientific Reports, English scientists concluded that two components of diesel exhaust — nitric oxide and nitrogen dioxide — could alter the odor of the chemicals that give a flower its smell.

This phenomenon, researchers said, could either hinder or prevent honeybees from reaching their target flowers, and, in the process, inhibit the pollination of food crops.

The economic value of pollination across the planet has been estimated at more than $200 billion a year, and 70 percent of the world’s food crops rely on this process, said lead study author Robbie Girling.

“Honeybees have a sensitive sense of smell and an exceptional ability to learn and memorize new odors, enabling them to use floral odors to help locate, identify and recognize the flowers from which they forage,” Girling wrote.

The researchers synthetically reproduced the odor of oilseed rape flowers. The scent is the result of eight chemicals mingling together, and researchers used these chemicals to reproduce the odor in the lab.

Next, they took worker honeybees that were raised at the University of Southampton and “taught” them to associate the synthetic odor with nectar. They did this by restraining the bees, exposing them to the smell and then swabbing their antennae with a sweet, nectarlike sucrose solution.

In the wild, worker honeybees will detect sweet nectar with their antennae. The bees then reflexively extend their proboscis — a long, hollow tongue — and suck up the liquid.

Study authors exposed the honeybees to the pure flower smell, as well as versions that were altered to mimic the effects of exposure to nitric oxide and nitrogen dioxide.

Researchers said flower odors that mimicked the effects of pollution were roughly half as likely to make the bees stick their tongues out than the unadulterated smell. Researchers deemed this a “ significant reduction in recognition.”